Work

Drying shrinkage performance of alkali-activated ground granulated blast-furnace slag governed by alkali-modulated viscoelastic relaxation

Year: 2026

Type: article

Abstract: The drying shrinkage of alkali-activated ground granulated blast-furnace slag (AAS) exhibits distinctive and more pronounced time-dependent behavior than ordinary Portland cement (OPC) pastes, yet how alkali impacts this behavior remains insufficiently understood. This study investigates the effect of alkali content on drying shrinkage of cementitious materials by comparing the performance of plain OPC (without external alkali addition), alkali-enriched OPC, and AAS pastes over a wide relative humidity (RH) range (12–85%). The results show that alkali-enriched systems demonstrate markedly different shrinkage responses even under similar cumulative moisture losses, whereas plain OPC paste maintains a comparatively consistent shrinkage–moisture-loss relationship. Viscoelastic analysis reveals that alkalis modify the time-dependent mechanical response of the cementitious solids, leading to larger delayed compliance and generally longer effective relaxation timescales. These changes enhance viscoelastic relaxation and stress-history effects, shifting drying shrinkage behavior from a moisture-loss-controlled regime toward a stress-driven, history-dependent response in alkali-enriched systems. The results further show that, under various drying conditions, the influence of alkalis is manifested through coupled changes in internal moisture state, pore structure, and pore-fluid thermodynamics, which together govern internal capillary-stress evolution. Consequently, drying-induced deformation increasingly depends on the evolution of capillary-stress history rather than on cumulative moisture loss alone. These findings demonstrate that the primary distinction between alkali-less and alkali-enriched systems lies in alkali-modulated viscoelastic relaxation.

Source: Cement and Concrete Composites

DOI: 10.1016/j.cemconcomp.2026.106651

Authors: Yuhui Lyu, Hailong Ye

Institution: University of Hong Kong

Language: English

Topic: Concrete Properties and Behavior

Subfield: Civil and Structural Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $5,120

Funders: Ministry of Science and Technology of the People's Republic of China, University of Hong Kong, State Key Laboratory for Disaster Reduction in Civil Engineering, National Key Research and Development Program of China